Conclusions
The obtained data have shown that indicators can be used in assessing land degradation and desertification risk for a wide range of physical environmental, social and economical conditions in the study sites. Based on the correlation coefficient values of indicators selected for each process, a small selection of indicators can be characterized as significantly related to human actions. Land degradation and desertification due to soil erosion in agricultural areas is predominately related to land use intensity, rate of land abandonment, and policy implementation. The indicators plant cover, tillage depth, allocated subsidies, and policy implementation are predominately related to land degradation in pastures. In forested areas in which soil erosion is the main process of land degradation and desertification risk is mainly related to the indicators: grazing intensity, rate of burned area, fire protection, and population density. Important indicators affecting tillage erosion in cropland and pastures are tillage operations, tillage depth, and land use intensity. The main indicators affecting land desertification in field sites where soil salinization is the main process of land degradation are water quality, groundwater exploitation, irrigation percentage of arable land, and population density. Land degradation and desertification due to water stress is predominately related to the indicators rate of burned area, tourism change, and policy implementation. Land degradation and desertification due to overgrazing is mainly related to the indicators fire frequency, fire protection, rate of burned area, rate of land abandonment, grazing intensity, farm size, and land fragmentation. The indicator grazing control and major land use been mainly related to desertification risk in areas where forest fires have been defined as the main cause of land degradation.
Finally, the comparative analysis has shown that indicators may be used worldwide for assessing desertification risk. The derived methodology may be used to assess the efficiency and efficacy of different land management practices and degradation monitoring techniques for combating desertification at farm level and given the pertinent information at even regional level, in a variety of locales. The derived system of indicators may enable land users to test different scenarios for ecosystem vulnerability in order to assess critical stress factors and their impacts on desertification. In this regard, the developed ES may allow the decision-makers worldwide to generate appropriate and timely desertification measures by estimating the risk of certain applied responses. It may also provide a standard for assessing the effectiveness of the various land management practices. For such an assessment, the developed expert system has the following advantages:
- presentation and evaluation of a variety of desertification indicators simultaneously;
- delineation of the desertification risk (results) in a concise and holistic fashion;
- direct association of data input to the sensitivity of the results;
- interdisciplinary criteria and evaluation process; and
- integration among experts, administrators and decision-makers, since input from each group is needed for a successful run of the algorithm.
